Classification of tumor samples from individuals is not an exact science. In many instances, accurate diagnosis and safe and effective treatment of a disorder depends on being able to discern biological distinctions among morphologically similar samples, such as tumor samples. The classification of a sample from an individual into particular disease classes has typically been difficult and often incorrect or inconclusive. Using traditional methods, such as morphology analyses, histochemical analyses, immunophenotyping and cytogenetic analyses, often only one or two characteristics of the sample are analyzed to determine the sample's classification, resulting in inconsistent and sometimes inaccurate results. Such results can lead to incorrect diagnoses and potentially ineffective or harmful treatment. Thus, a need exists for accurate markers for identifying tumor classes and classifying tumor samples.